a) Field of the Invention
The present invention relates to apparatus and method for controlling a driving force for a vehicle. The present invention particularly relates to control apparatus and method in which an engine (output) torque is controlled in such a manner that the engine torque provides a driver's demanding torque in accordance with a driver's intention (accelerator operation situation) when no driving force control is executed, the engine torque provides a target engine torque derived from a predetermined driving force control when the driving force control is executed and which have improved reliabilities of control.
b) Description of the Related Art
It is well known that, in a case where excessive slip occurs on drive wheels during a vehicular acceleration, an opening angle of an engine throttle valve is not determined in a direct accordance with a manipulation of an acceleration by a vehicular driver but a traction control is executed such that the opening angle of the throttle valve and/or the number of engine cylinders to which an air-fuel mixture fuel supply is cut off is controlled on a basis of a target engine output torque which is derived so that the slip is suppressed and the driving force is stably transmitted on a road surface. The traction control system described above is normally abbreviated as TCS.
In addition to an engine controller which is enabled to adjust over an engine driving force to adjustably increase or decrease the opening angle of the throttle valve and the number of engine cylinders for which the fuel supply out-off is carried out, a TCS controller is provided. The TCS controller determines a slip condition of drive wheels on the basis of a difference in road wheel velocities between the drive wheels and non-drive wheels, executes the driving force control in a case where the slip condition is excessively large, calculates an appropriate opening angle of the engine throttle valve such as to enable the suppression of the excessive slip, and outputs a signal representing the calculated opening angle of the throttle valve to an engine (output) controller.